A command line interface (CLI) is a way of interacting with a computer program where a user issues commands to the program in the form of successive lines of text. A CLI is used for modern network operating of network devices to allow a user to interact with that operating system. This is used to perform day-to-day management of the network device once the user logins into the network operating system. Traditional CLI requires the user to use special tools like secure shell (SSH) or telnet to login and needs to run from desktop machines.
However, a user may not know all the commands available and will need to explore the CLI by entering partial commands. Another way to understanding the semantics of a CLI is use an online help provided by the CLI (e.g., --help, -h or /? for each and every command). Online CLI help systems tend to be difficult to use, because the CLI help system will describe how to use a CLI command, but not in the context of the configured network system. In addition, the availability of a CLI help system may not address the problem completely. CLI commands further require extensive documentation to specify the list of all commands supported by the system. In addition, a CLI requires special tools to access and making it not accessible from modern mobile devices like tablets and phones. To connect to CLI the user has to buy expensive tools or applications that support secure SSH or telnet connection.